Shaped silicon ingot using layer transfer

ABSTRACT

A shaped crystalline ingot for an ion cleaving process has a major surface that is substantially planar, a first side face that is substantially planar along a first direction orthogonal to the major surface, and a second side face that is substantially planar along a second direction orthogonal to the major surface. The ion cleaving process is a process in which ions are implanted into the shaped crystalline ingot to form a cleave plane that separates a substrate comprising the major surface from the shaped crystalline ingot.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 15/264,525, filed Sep. 13, 2016, which is acontinuation application of U.S. patent application Ser. No. 14/106,002,filed Dec. 13, 2013, now issued as U.S. Pat. No. 9,460,908 on Oct. 4,2016, which is a continuation of U.S. patent application Ser. No.12/384,926, filed Apr. 10, 2009, now issued as U.S. Pat. No. 8,623,137on Jan. 7, 2014, which claims priority to U.S. Provisional PatentApplication No. 61/051,344, filed May 7, 2008, all of which areincorporated by reference in their entirety herein for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates generally to techniques for formingsubstrates using a layer transfer technique and a shaped ingot. Moreparticularly, the present method and system provides a layer transferprocess for slicing a single crystal silicon sheet from a shaped siliconingot for a variety of applications including photovoltaic cells. Merelyby example, the present invention provides a method of usingpreferential cleave planes in single crystal silicon with a patternedimplant to produce single crystal silicon sheets in a highly efficientcontrolled cleaving process. But it will be recognized that theinvention has a wider range of applicability.

From the beginning of time, human beings have relied upon the “sun” toderive almost all useful forms of energy. Such energy comes frompetroleum, radiant, wood, and various forms of thermal energy. As merelyan example, human beings have relied heavily upon petroleum sources suchas coal and gas for much of their needs. Unfortunately, such petroleumsources have become depleted and have led to other problems. As areplacement, in part, solar energy has been proposed to reduce ourreliance on petroleum sources. As merely an example, solar energy can bederived from “solar cells” commonly made of silicon.

The silicon solar cell generates electrical power when exposed to solarradiation from the sun. The radiation interacts with atoms of thesilicon and forms electrons and holes that migrate to p-doped andn-doped regions in the silicon body and create voltage differentials andan electric current between the doped regions. Solar cells have beenintegrated with concentrating elements to improve efficiency. As anexample, solar radiation accumulates and focuses using concentratingelements that direct such radiation to one or more portions of activephotovoltaic materials. Although effective, these solar cells still havemany limitations.

As merely an example, solar cells often rely upon starting materialssuch as silicon. Such silicon is often made using either polysilicon(i.e. polycrystalline silicon) and/or single crystal silicon materials.These materials are often difficult to manufacture. Polysilicon cellsare often formed by manufacturing polysilicon plates. Although theseplates may be formed effectively in a cost effective manner, they do notpossess optimum properties for highly effective solar cells. Inparticular, polysilicon plates do not exhibit the highest possibleefficiency in capturing solar energy and converting the captured solarenergy into usable electrical power. By contrast, single crystal silicon(c-Si) has suitable properties for high grade solar cells. Such singlecrystal silicon is, however, expensive to manufacture and is alsodifficult to use for solar applications in an efficient and costeffective manner.

Additionally, both polysilicon and single-crystal silicon materialssuffer from material losses during conventional manufacturing singlecrystal silicon substrates, where a sawing process is used to physicallyseparate thin single crystal silicon layers from a single crystalsilicon ingot originally grown. For example, inner diameter (ID) sawingprocess or wire sawing process eliminates as much as 40% and even up to60% of the starting material from a cast or grown boule and singulatethe material into a wafer form factor. This is a highly inefficientmethod of preparing thin polysilicon or single-crystal silicon platesfor solar cell use.

To overcome drawbacks of using silicon materials, thin-film solar cellshave been proposed. Thin film solar cells are often less expensive byusing less silicon material or alternative materials but their amorphousor polycrystalline structure are less efficient than the more expensivebulk silicon cells made from single-crystal silicon substrates. Theseand other limitations can be found throughout the present specificationand more particularly below.

From the above, it is seen that techniques to manufacture suitable highquality single crystal silicon sheets with low cost and highproductivity are highly desired.

BRIEF SUMMARY OF THE INVENTION

The present invention relates generally to techniques for formingsubstrates using a layer transfer technique. More particularly, thepresent method and system provides a layer transfer process for slicinga single crystal silicon sheet from an shaped silicon ingot for avariety of applications including photovoltaic cells. Merely by example,the present invention provides a method of using preferential cleaveplanes in single crystal silicon with a patterned implant to producesingle crystal silicon sheets in a highly efficient controlled cleavingprocess. But it will be recognized that the invention has a wider rangeof applicability.

In a specific embodiment, the present invention provides a method forslicing a shaped silicon ingot. The method includes providing a singlecrystal silicon boule characterized by a cropped structure including afirst end-face, a second end-face, and a length along an axis in an<100> crystallographic direction substantially vertically extending fromthe first end-face to the second end-face. The method further includescutting the single crystal silicon boule substantially through an {110}crystallographic plane in parallel to the axis to separate the singlecrystal silicon boule into a first portion with a first surface and asecond portion with a second surface. Additionally, the method includesexposing either the first surface of the first portion or the secondsurface of the second portion. Moreover, the method includes performinga layer transfer process to form a single crystal silicon sheet fromeither the first surface of the first portion or from the second surfaceof the second portion. In an embodiment, the layer transfer processincludes one or more implanting process and one or more cleaving processwhich can be repeated in a successive manner to produce a plurality ofsingle crystal silicon sheets with surfaces in {110} crystallographicplanes.

In another specific embodiment, the present invention provides a methodfor slicing a shaped silicon ingot. The method includes providing asingle crystal silicon ingot characterized by a cropped structureincluding a first end-face, a second end-face, and a length along anaxis in an <110> crystallographic direction substantially verticallyextending from the first end-face to the second end-face. The methodfurther includes clamping the single crystal silicon ingot near avicinity of the second end-face. Additionally, the method includesdetermining a first side associated with a first edge thickness from thefirst end-face to a first {110} crystallographic plane and a second sideassociated with a second edge thickness from the first end-face to thefirst {110} crystallographic plane. The first end-face is off a miscutangle from the first {110} crystallographic plane and the first edgethickness is smaller than the second edge thickness. The method furtherincludes applying a patterned ion-implantation at the vicinity of thefirst side to form a first cleave region at substantially the first edgethickness below the first end-face. Moreover, the method includescleaving a layer of single crystal silicon material from the first sideto the second side through the first {110} crystallographic planeinitiated at the first cleave region. The method further includesapplying a patterned ion-implantation at the vicinity of the second sideto form a second cleave region at a predetermined thickness below thefirst {110} crystallographic plane. Furthermore, the method includescleaving a single crystal silicon sheet from the second side to thefirst side through a second {110} crystallographic plane initiated atthe second cleave region. The second {110} crystallographic plane is inparallel to the first {110} crystallographic plane.

In yet another specific embodiment, the present invention provides amethod for slicing a shaped silicon boule. The method includes providinga single crystal silicon boule characterized by a cropped structureincluding a first end-face, a second end-face, and a length along anaxis in an <110> crystallographic direction substantially verticallyextending from the first end-face to the second end-face. The methodfurther includes cutting the single crystal silicon boule substantiallyalong an {111} crystallographic plane in parallel to the axis to form afirst portion with a first surface. The first surface is off a miscutangle from the {111} crystallographic plane. Additionally, the methodincludes determining a first side associated with a first edge thicknessfrom the first surface to a first {111} crystallographic plane withinthe first portion and a second side associated with a second edgethickness from the first surface to the first {111} crystallographicplane. The first edge thickness is smaller than the second edgethickness. The method further includes performing a first implantingprocess to form a first cleave region near a vicinity of the first sideat the first edge thickness below the first surface. Moreover, themethod includes performing a first cleaving process to remove a layer ofsingle crystal silicon material from the first side to the second sidethrough the first {111} crystallographic plane. The first cleavingprocess is initiated at the first cleave region. The method furtherincludes performing a second implanting process to form a second cleaveregion near a vicinity of the second side at a predetermined thicknessbelow the first {111} crystallographic plane. Furthermore, the methodincludes performing a second cleaving process to remove a single crystalsilicon sheet through a second {111} crystallographic plane, the secondcleaving process being initiated at the second cleave region.

Many benefits can be obtained by implementing the present invention. Fortypical single crystal silicon ingot grown with an axis in <100>crystallographic direction, the present invention provides a method toform a portion of silicon ingot or boule with a surface substantially inan {110} type plane. This portion of silicon boule with such a surfacecan be used to produce a plurality of single crystal silicon sheets insubstantially squared shape by an advanced layer transfer process.Taking advantage of the easier-cleave characteristic of {110} typeplane, the layer transfer process can be performed with lower ion dosein a patterned ion-implantation process and higher yield in subsequentcleaving process. The resulted single crystal silicon sheet with {110}surface plane can have much lower surface roughness than a sheet cleavedfrom (100) plane. In addition, for silicon ingot grown in <110>direction, instead of one way to cleave layers of single crystal siliconmaterial from an {110} plane, a plurality of single crystal siliconsheet with an {111} surface plane can be produced according embodimentsof the present invention. In fact, {111} plane is the best cleave planefor single crystal silicon. Additionally, the single crystal siliconsheets with {110} or {111} type surface planes formed according toembodiments of the present invention can be further processed to formone or more photovoltaic regions on the {110} or {111} type planes. Theresulted process conditions are similar to those for substrates with(100) surface planes, while the overall manufacture cost is reduced.Particularly, when compared to multi-crystal silicon substrate used fortypical photovoltaic cells the single crystal silicon sheet substrateprovides much better quality in terms of surface roughness, surfacecleanliness, line-width for metallization, cell consistency inelectrical characteristics, and the overall lifetime andlight-conversion efficiency (20% vs. 15%), and at the same time witheven lower cost per wafer. Some embodiments of the invention can utilizethe existing manufacture processing systems and techniques as well astake some advantage of certain newly developed techniques formanufacturing thin wafer/substrate for various semiconductor deviceapplications. More details about various embodiments of the presentinvention can be found in the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram of a shaped single crystal silicon boulewith a long axis in an <100> crystallographic direction verticallyextending from two end-faces provided according to an embodiment of thepresent invention;

FIG. 2 is a simplified diagram of a portion of the shaped single crystalsilicon boule obtained by cutting along a plane in FIG. 1 to expose asurface substantially in an {110} crystallographic plane according to anembodiment of the present invention;

FIGS. 3A-3F are simplified diagrams showing a layer transfer processperformed on an exposed single crystal silicon surface according to anembodiment of the present invention;

FIG. 4 is an exemplary diagram of a shaped single crystal silicon boulewith a long axis in an [110] crystallographic direction verticallyextending from two end-faces provided according to an embodiment of thepresent invention;

FIG. 5A is a simplified diagram showing a portion of the shaped singlecrystal silicon boule with a surface substantially in an {111} typeplane according to an embodiment of the present invention;

FIG. 5B is a simplified diagram showing a single crystal silicon sheetwith {111} planes being removed from the portion shown in FIG. 5A by alayer transfer process according to an embodiment of the presentinvention;

FIG. 6 is a simplified diagram showing one or more single crystalsilicon sheets being sliced from the end-face of a shaped single crystalsilicon ingot in an <110> or <111> crystallographic direction accordingto an embodiment of the present invention;

FIG. 7 is a simplified flowchart showing a method of slicing a shapedcrystal ingot according to an embodiment of the present invention;

FIG. 8 is a simplified flowchart showing a method of slicing a shapedcrystal ingot according to another embodiment of the present invention;

FIG. 9 is a simplified flowchart showing a method of slicing a shapedcrystal ingot according to an alternative embodiment of the presentinvention;

FIG. 10 is a simplified diagram showing a 4×4 tray arrangement ofsilicon ingots for forming spot initiation of cleave regions usingpatterned ion implantation according to an alternative embodiment of thepresent invention; and

FIG. 11 is a simplified diagram showing a 4×4 tray arrangement ofsilicon ingots for forming line initiation of cleave regions usingpatterned ion implantation according to an alternative embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to techniques for formingsubstrates using a layer transfer technique. More particularly, thepresent method and system provides a layer transfer process for slicinga single crystal silicon sheet from an shaped silicon ingot for avariety of applications including photovoltaic cells. Merely by example,the present invention provides a method of using preferential cleaveplanes in single crystal silicon with a patterned implant to producesingle crystal silicon sheets in a highly efficient controlled cleavingprocess. But it will be recognized that the invention has a wider rangeof applicability.

As background, for a typical single crystal silicon ingot used formanufacturing wafer substrates, it is usually grown along an <100>crystallographic axis with an end facet being an {100} crystallographicplane. The wafer substrates produced by slicing the ingots thus have asurface substantially in an {100} crystallographic plane with a certainmiscut angle. However, {100} crystallographic plane is not a stablecleave plane which usually will branch into an {110} and an {111} plane,as we discovered. A solution is to increase ion dose and extend theimplanting area during the implanting process to create a cleave regionthat is more susceptible for cleaving. However, it still causes highersurface roughness, more cost with high ion dose and less productivity,and perhaps lower yield when slicing the <100> orientation ingot inconvention manner. Depending upon the embodiment, these and otherlimitations are overcome using the present method and structures.

FIG. 1 is a simplified diagram of a shaped single crystal silicon boulewith a long axis in an <100> crystallographic direction verticallyextending from two end-faces provided according to an embodiment of thepresent invention. This diagram is merely an example, which should notunduly limit the scope of the claims herein. One of ordinary skill inthe art would recognize many variations, alternatives, andmodifications. As shown, a shaped single crystal silicon boule 100 is acylinder with an axis in an <100> crystallographic direction, includingtwo end-faces 11 and 12, four major side-faces 21, 22, 23, and 24, andfour minor side-faces (or corner faces) 31, 32, 33, and 34. The twoend-faces 11 and 12 are substantially perpendicular to the axis, so thateach of them basically is one of {100} crystallographic plane. Forexample, if the axis is in [100] direction, the end-face should be in(100) plane. The side planes are also substantially in parallel to theaxis. For example, if the axis is in [100] direction, the four majorside-faces can be in one of {110} crystallographic planes. The singlecrystal silicon boule 100 also includes a length 45 defined as adistance between the two end-faces 11 and 12. In one embodiment, whencropping a single crystal silicon ingot to provide the boule 100structure, the cropping/cutting process controls can be done preciselyto have both the side-faces and the end-faces being substantially alongcertain crystallographic planes as mentioned and to have the length 45of the boule being substantially equal to a lateral dimension of theend-face. Of course, there can be many alternatives, variations, andmodifications.

Additionally, FIG. 1 also shows that a virtual middle plane, asindicated by number 40, across the two end-faces 11 and 12 along theaxis <100> can be in one of {110} crystallographic plane and selected asa cutting plane. A wire saw process can be applied to cut the boule 100through the selected cutting plane 40 to separate the boule 100 into twoportions. FIG. 2 is a simplified diagram of a portion of the shapedsingle crystal silicon boule obtained by cutting along a plane in FIG. 1to expose a surface substantially in an {110} crystallographic planeaccording to an embodiment of the present invention. This diagram ismerely an example, which should not unduly limit the scope of the claimsherein. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications. As shown, the portion 200forms after cutting the single crystal silicon boule 100 through theplane 40. Two end-faces 11 and 12 of boule 100 now become side face 11 aand side face 12 a (12 a is not directly viewable in FIG. 2) and twoside faces 21 and 23 now are cut with portions 21 a and 23 a left (again23 a is not directly viewable). In particular, the portion 200 includesa newly formed surface 41 by cutting through the plane 40. The surface41 is in substantially a squared shape. In a specific embodiment, thesurface 41 can be used as a base plane for further slicing a pluralityof single crystal silicon films/substrates in an advanced layer transferprocess. In another specific embodiment, the minor side face 34 (and 33,not directly viewable) can be used for clamping the portion 200 duringthe layer transfer process.

In conventional wafer manufacturing processes, wafer substrates forvarious semiconductor industrial applications including photovoltaiccells are vertically sliced one by one from the end-face of the singlecrystal silicon ingots or boules. If the long axis of the ingot is along<100> crystallographic direction, the wafer substrate obtained wouldhave a surface substantially in an {100} crystallographic plane.Usually, the cutting is imperfect so that the surface actually is off amiscut angle from the {100} plane along a certain direction (forexample, a [110] direction). Typically, the miscut angle is within 0 to2 degrees. Embodiments of the present invention suggests an alternateapproach to prepare the single crystal silicon boule to be used forslicing wafer/substrates from. By cutting the boule 100 with a long axisin <100> direction into two portions along a predetermined plane 40 in{100} plane, each of two resulting portions provides a new surfacesubstantially in an {110} crystallographic plane rather than a {100}plane. In particular, the new surface has a substantially squared shapeif the single crystal silicon boule 100 is properly provided. Also, thenew surface may be off the {110} crystallographic plane by a smallmiscut angle within 0 to 2 degrees. In a specific embodiment, this newsurface is more suitable for forming a plurality of shaped silicon sheetmaterials by slicing the portion 200 one by one using an advance layertransfer process developed by a co-inventor, which greatly reduces thekerf-loss compared to the conventional wafer cutting techniques. Moredetails of the layer transfer process can be found in a co-assigned U.S.patent application Ser. No. 11/935,197 by Francois J Henley et al., andtitled “METHOD AND STRUCTURE FOR THICK LAYER TRANSFER USING A LINEARACCELERATOR”, filed on Nov. 5, 2007. More descriptions and theadvantages of the layer transfer process utilizing {110}crystallographic plane can be found throughout this specification andspecifically below.

FIGS. 3A-3F are simplified diagrams showing a layer transfer processperformed on an exposed single crystal silicon surface according to anembodiment of the present invention. These diagrams are merely examples,which should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. As shown in FIG. 3A, a cross section of a singlecrystal silicon boule 300 includes an exposed surface 311, while theopposite surface may be clamped on a stage within a system (not shown)configured to perform a layer transfer process. Also shown, the singlecrystal silicon boule 300 includes a crystallographic plane 315 locatedin certain depth below the surface 311, forming a layer 310 of singlecrystal silicon material located near the top portion of the siliconboule 300. For example, the plane 315 is an {110} crystallographic planeor an {111} crystallographic plane. In one example, the surface 311 isthe created surface 41 of the cut portion 200 of the single crystalsilicon boule 100. Due to a small miscut angle between the surface 311and the crystallographic plane 315, the layer 310 has an edge side witha thinner edge thickness and an opposite edge side with a thicker edgethickness, as shown in FIG. 3A. In one embodiment, the edge side withthinner edge thickness can be identified using an X-ray diffraction andother techniques.

After the edge side with thinner edge thickness is identified, theexposed surface of the single crystal silicon boule (or a portion of it)can be applied with a first ion-implanting process. In particular, thefirst ion-implanting process is a patterned implantation process withonly the vicinity of the edge side with the thinner edge thicknessexposed to an ion beam. As shown in FIG. 3B, an ion beam 320 isintroduced to irradiate an area near the vicinity of the edge sideidentified with a thinner edge thickness. In one embodiment, the ionbeam 320 is introduced from above the surface 311 in a substantiallyvertical angle. In another embodiment, the ion beam 320 is generated bya RFQ or RFI based linear accelerator system to possess an energy levelabout 1-5 MeV and well controlled other parameters including beam size,pulse rate, etc so that they can be implanted into the single crystalsilicon boule 300 with a desired depth. In one example, the controlledion beam 320 implants protons into a region at the thinner edgethickness below the surface 311, where a cleave region 321 is formed.Referring to the co-assigned U.S. patent application Ser. No. 11/935,197by Francois J Henley et al., and titled “METHOD AND STRUCTURE FOR THICKLAYER TRANSFER USING A LINEAR ACCELERATOR”, filed on Nov. 5, 2007, moredetails about the ion-implanting process as well as the formation of thecleave region can be found. In particular, this cleave region includes alocal defect network that is susceptible of initiating a bond-breakingcleavage process such as a Controlled Cleave Process (CCP) developed bya co-inventor.

In one embodiment, FIG. 3C shows a first cleaving process is performed.As shown, the first cleaving process is initiated at the cleave region321 and utilized a blade 340 with sharp edge to push into a gap createdfrom the cleave region 321. As mentioned above, the cleave region 321 isat the thinner edge thickness which becomes part of the crystallographicplane 315. In one embodiment, the first cleaving process includespushing the blade 340 through the crystallographic plane 315 from theedge side with thinner edge thickness to the opposite edge side withthicker edge thickness. For example, the blade is coupled to a robotsystem that allows the pushing process to be under controlled. Inanother embodiment, the process of pushing blade through is accompaniedwith another process of pulling film up to lift the layer 310 from theportion above the inserted blade edge. For example, a vacuum chucking orelectrostatic chucking method can be applied to lift the layer 310 awayfrom the remaining silicon boule portion 300 a in the pulling film upprocess. In yet another embodiment, the first cleaving process isassisted by applying ultrasonic and mechanical energy for both theprocess of pushing blade through and the process of pulling film up.

In a specific embodiment, the first cleaving process with the assistanceof ultrasonic mechanical energy is able to break atomic bonds alongcertain crystallographic planes that cost the least energy. For singlecrystal silicon, the lower surface energy of {111} type plane, followedby {110} type plane, is the best cleave plane. While the {100} typeplane is not a stable cleave plane because it can branch tocorresponding (110) and (111) plane sections, resulting a much higherroughness and lower cleave yield. Therefore, as the crystallographicplane 315 is selected to be an {110} plane or an {111} plane, the firstcleaving process through the plane 315 as proceeding in FIG. 3C wouldresult a removal of the layer 310 and create a new surface 316 for theremaining portion of silicon boule 300 a. FIG. 3D provides a crosssection view of the remaining silicon boule 300 a with a newly formedsurface 316 by the first cleaving process after the layer 310 isremoved. In one embodiment, the newly formed surface 316 issubstantially the same crystallographic plane as the plane 315. Forexample, the surface 316 can be an {110} crystallographic plane or an{111} crystallographic plane, depending on how the silicon boule 300 isprovided. Of course, there are many alternatives, variations, andmodifications.

FIG. 3E shows that the remaining portion 300 a with an exposed surface316 is ready for a second ion-implanting process. In one embodiment, thesecond ion-implanting process is another patterned ion-implantationprocess substantially the same as the first ion-implanting process. Asshown, an ion beam 330 is introduced to irradiate an area near thevicinity of the edge side that was associated with a thicker edgethickness before removal of the layer 310. The patternedion-implantation causes a formation of a cleave region 331 at athickness below the surface 316. The thickness can be controlled byadjusting the parameters of ion-beam 330. In one embodiment, thethickness is a distance between the surface 316 and a plane 317. Theplane 317 is a same type crystallographic plane as the surface 316 andis in parallel to the surface 316. For example, either plane 317 orsurface 316 is an (110) plane. In another example, both plane 317 andsurface 316 are a (−11−1) plane belonging to the {111} plane family. Asshown in FIG. 3E, a cleave region 331 is formed by the secondion-implanting process to associate the plane 317 and a top layer 311with the thickness of single crystal silicon material between thesurface 316 and the plane 317 is defined on top of the silicon bouleportion 300 a.

In one embodiment, the silicon boule portion 300 a with the cleaveregion 331 is further subjected to a second cleaving process initiatedfor the cleave region 331. In another embodiment, the second cleavingprocess is substantially the same as the first cleaving process,resulting a removal of the layer 311 from the silicon boule portion 300a through the crystallographic plane 317. FIG. 3F shows a remainingsilicon boule portion 300 b after the layer 311 is removed, revealing anew surface 318 for the silicon boule portion 300 b. In one embodiment,the removed layer 311 is a shaped single crystal silicon sheet withsurfaces substantially the same as predetermined crystallographic plane317 or plane 316 and a substantially a squared shape. For example, thecrystallographic plane type can be {110} or {111} as desired. In anotherexample, the shaped single crystal silicon sheet can be applied forvarious semiconductor device applications including photovoltaic cells.The thickness of the shaped single crystal silicon sheet can be formedin a range from 20 microns to 180 microns for different applications. Inyet another embodiment, the newly remaining silicon boule portion 300 bcan be further subjected for a series of combinations of ion-implantingprocess and cleaving process in a successive manner so that a pluralityof the shaped single crystal silicon sheets (like the layer 311) can beproduced.

In one embodiment, the shaped single crystal silicon ingot or boule canbe provided with different orientations. For example, depending on theuse of different seed crystal, the single crystal silicon ingot can beproduced using an ingot growth process, such as a Czochralski process,to have its long axis in either <100> crystallographic direction, or<110> direction, or <111> direction, or others. After proper sidecropping and end cutting, a single crystal silicon boule that is similarto but different from the silicon boule 100 can be provided and commonlyavailable from the single crystal silicon manufacturers. FIG. 4 is anexemplary diagram of a shaped single crystal silicon boule provided witha long axis in an [110] crystallographic direction vertically extendingfrom two end-faces according to an embodiment of the present invention.This diagram is merely an example, which should not unduly limit thescope of the claims herein. One of ordinary skill in the art wouldrecognize many variations, alternatives, and modifications.

As shown in FIG. 4, a shaped single crystal silicon boule 400 is acylinder with an axis in [110] crystallographic direction, including twoend-faces 55 and 56, four major side-faces 61, 62, 63, and 64, and fourminor side-faces (or corner faces) 71, 72, 73, and 74. The two end-faces55 and 56 are substantially perpendicular to the [110] axis, so thateach of them basically is in the (110) crystallographic plane. Theside-faces are also substantially in parallel to the axis. Inparticular, a major side-face 62 is preferably selected to be in (−11−1)plane. Another major side-face 64 is in parallel to side-face 62. Theother two major side-faces 61 and 63 are in parallel to each other butperpendicular to the major side-face 62. As shown, the crystallographicdirection [41-1] is perpendicular to the side-face 62 and alsoperpendicular to the crystallographic direction [110] of the axis. Thus,a middle cross section plane 80, which contains the long axis andperpendicular to the [41-1] direction, should also be in a planebelonging to {111} family. Additionally, the single crystal siliconboule 400 includes a length 85 defined as a distance between the twoend-faces 55 and 56. In one embodiment, when cropping a single crystalsilicon ingot to provide the boule 400 structure, the cropping/cuttingprocess controls can be done to have the length 85 of the silicon boule400 being substantially equal to a lateral dimension of the end-face 55or the cross section plane 80.

In one embodiment, the single crystal silicon boule 400 as provided canbe cut along the cross section plane 80 to form two portions each with anew surface that is substantially in a crystallographic plane belong to{111} family. The resulting portion with the new surface exposed forperforming a layer transfer process to produce one or more shaped sheetmaterial having an alternative crystallographic plane than conventional(110) plane. FIG. 5A is a simplified diagram showing a portion of theshaped single crystal silicon boule with a surface substantially in an{111} type plane according to an embodiment of the present invention.This diagram is merely an example, which should not unduly limit thescope of the claims herein. One of ordinary skill in the art wouldrecognize many variations, alternatives, and modifications. As shown,the silicon boule portion 500 includes a top surface 81 and twoend-faces (one end-face 55 a is visible and an opposite one is notvisible in FIG. 5A) as well as several other side-faces. In oneembodiment, the silicon boule portion 500 can be obtained by cutting thesingle crystal silicon boule 400 along the middle cross section plane80. Therefore, the top surface 81 is created from the cross sectionplane 80, and the end-face 55 a is part of the original end-face 55 andthe side-face 61 a is part of original side-face 61. As indicated by thedirectional arrow, the surface 81, which is substantially perpendicularto the [−11−1] direction, is substantially in (−11−1) plane whichbelongs to {111} plane family. Of course, there can be manyalternatives, variations, and modifications. For example, there can be amiscut angle, typically within 0 to 2 degrees, between the surface 81and the (−11−1) crystallographic plane.

FIG. 5B is a simplified diagram showing a single crystal silicon sheetwith {111} planes being removed from the portion shown in FIG. 5A by alayer transfer process according to an embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize many variations, alternatives, and modifications. In oneembodiment, the layer transfer process performed on the portion 500 issubstantially the same as that described in FIGS. 3A-3F. In a specificembodiment, the cleaving process is performed to remove a shaped sheetmaterial 511 through an {111} crystallographic plane. In anotherembodiment, the shaped sheet material is a substantially a squared shapehaving a thickness between a front surface and a back surface which areboth in parallel to a substantially {111} crystallographic plane. Forexample, the {111} plane is the (−11−1) plane in FIG. 5B. After removingthe shaped sheet material, the silicon boule portion 500 becomes asilicon boule portion 500 a with a newly created surface 82 which isalso substantially in a plane belonging to {111} family. In a successivemanner, the layer transfer process can be further applied to the siliconboule portion 500 a to continue producing more single crystal siliconsheets like the shaped sheet material 511.

In an alternative embodiment, the provided single crystal silicon boulehas a long axis in either <110> or <111> crystallographic directionextending vertically through two end-faces. Thus the two end-faces canbe substantially in {110} or {111} crystallographic planes, whichautomatically become the base plane for layer transfer process becauseboth type of crystallographic planes are preferred for cleaving. FIG. 6is a simplified diagram showing one or more single crystal siliconsheets being sliced from the end-face of a shaped single crystal siliconingot in an <110> or <111> crystallographic direction according to anembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. As shown, a shaped sheet material 611 is formed witha surface 91 substantially in an {110} or {111} crystallographic plane.Following that, another shaped sheet material 612 is formed with asurface 92 substantially also in an {110} or {111} crystallographicplane. The remaining portion 600 b of the single crystal silicon ingothas a surface 93 still substantially in an {110} or {111}crystallographic plane. In one embodiment, the slicing process to formone or more shaped sheet material out of the single crystal siliconingot is performed by a layer transfer process described in FIGS. 3A-3F.In a specific embodiment, the formed shaped sheet material has athickness in a range of 20 microns to 180 microns for varioussemiconductor device applications including photovoltaic cells. Forexample, for each of the f shaped sheet material, one or morephotovoltaic regions can be formed on the {110} or {111}crystallographic planes.

FIG. 7 is a simplified flowchart summarizing a method of slicing ashaped crystal ingot according to an embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize many variations, alternatives, and modifications. Asshown, the method 700 includes a process of providing a single crystalsilicon boule with an axis in <100> direction (Process 710).Additionally, the single crystal silicon boule may be cut from an ingotto have a first end-face and a second end-face substantially in {100}crystallographic plane and have a length between the first end-face andthe second end-face. Additionally, the single crystal silicon boule canbe cropped on its sides along certain crystallographic planes. Forexample, the cropping crystallographic planes can be selected from the{110} plane family. In one example, two opposite cropped side planes arein (110) planes and other two opposite cropped side planes are in (−110)planes so that the single crystal silicon boule becomes the siliconboule 100 shown in FIG. 1 with its cross-section in a substantiallysquared shape (excepting for chopped corners). In another example, thecutting method used here can be conventional ID sawing or wire sawingmethod.

FIG. 7 further shows a process (712) of the method 700 to cut the singlecrystal silicon boule substantially through an {110} crystallographicplane in parallel to the axis to form a first portion and a secondportion. In a specific embodiment, either the first portion or thesecond portion has a newly created surface by cutting through the {110}crystallographic plane. The newly created surface is substantially inthe {110} crystallographic plane, with a possibly small miscut angletowards a certain direction due to imperfect cutting. Typically, themiscut angle can be within 2 degrees. This cutting can still beperformed using conventional wire sawing method.

Now the newly created surface that is substantially parallel to an {110}crystallographic plane can be exposed (Process 714) and aligned tocertain direction when either the first portion or the second portion isproperly clamped on a processing stage. For example, the portion 200 isused with its surface 41 being exposed and the minor side face 34 beingused for clamping. Subsequently, a layer transfer process can beperformed on either the first portion or the second portion to form asingle crystal silicon sheet from the exposed surface (Process 716). Ina specific embodiment, the layer transfer process includes a series ofsteps described in FIGS. 3A-3F. In particular, the single crystalsilicon sheet removed from either the first portion or the secondportion includes surfaces in {110} crystallographic planes which arerelatively easier to be cleaved according to certain embodiments of thepresent invention. In another embodiment, the formed single crystalsilicon sheets with {110} planes have a squared shape providing a moreefficient module area utilization for manufacture of photovoltaic cells.

FIG. 8 is a simplified flowchart showing a method of slicing a shapedcrystal ingot according to another embodiment of the present invention.This diagram is merely an example, which should not unduly limit thescope of the claims herein. One of ordinary skill in the art wouldrecognize many variations, alternatives, and modifications. As shown,the method 800 includes a process of providing a single crystal siliconingot with an axis in <110> direction, a first end-face, and a secondend-face (Process 810). In this process, an silicon ingot can be grownspecifically along an <110> crystallographic direction. Then the ingotis cut along a first cross section plane substantially perpendicular tothe <110> direction to have a first end-face and cut along a secondcross section plane substantially perpendicular to the <110> directionto have a second end-face. The cutting method can be simply aconventional ID sawing or a wire sawing technique. In a specificexample, the ingot is a silicon boule 400 shown in FIG. 4 with an axisin [110] direction and end-faces in (110) plane.

The method 800 then includes a process (812) of clamping the singlecrystal silicon ingot near a vicinity of the second end-face. Thisprocess is for preparing the silicon ingot for subsequent processes tobe performed near the first end-face. Firstly, a process (814) ofdetermining a first side near the first end-face associated with a firstedge thickness and a second side near the first end-face associated witha second edge thickness is carried out. The first edge thickness isdefined as a thickness, near a first side edge of the ingot, between thefirst end-face and a first {110} crystallographic plane below the firstend-face. The second edge thickness is defined as a thickness, near asecond side edge of the ingot, between the first end-face and the first{110} crystallographic plane below the first end-face. Due to theimperfect cutting (performed in process 810) the first end-face can beoff a small miscut angle from the true {110} crystallographic plane. Themiscut angle typically can be within 0 to 2 degrees towards a certaincrystallographic direction. Therefore, the first edge thickness can bedifferent from the second edge thickness due to the small miscut angle.In one example, the first edge thickness is smaller than the second edgethickness. In another example, the miscut angle is in an <110>crystallographic direction. In one embodiment, the determining the firstside is based on identifying the edge thickness using an X-rayDiffraction method or similar techniques.

The method 800 further includes a process (816) of applying a firstpatterned ion-implantation at the vicinity of the first side to form afirst cleave region at the first {111} plane below the first end-face.In one example, the first patterned ion-implantation can be performedfollowing a step described partly in FIG. 3B. In particular, the firstcleave region is located at a depth below the first end-face, where thedepth is substantially equal to the first edge thickness identified inProcess 814. Subsequently a first cleaving process (Process 818) can beperformed to initiate an film cleavage at the first cleave region orcause a removal of a layer of single crystal silicon material from thefirst side to the second side through the first {110} crystallographicplane. The first cleave region becomes a starting site for inserting ablade with sharp edge which is gradually pushed through the first {110}crystallographic plane while the layer of single crystal siliconmaterial is lifted or pulled up at the same time. In one embodiment,ultrasonic mechanical energy may be added to assist the blade-pushingand film-pulling-up processes. Additionally, air pressure can beinjected through blade for proving further assistance to the cleavingprocess. In one example, the Process 818 is performed according to stepdescribed in FIG. 3C.

The first cleaving process (818) creates a new surface that ischaracterized by the first {110} crystallographic plane. Subsequently, asecond patterned ion-implantation process (820) can be performed nearthe second side vicinity. In one embodiment, the second patternedion-implantation results a formation of a second cleave region locatedat a depth below the newly created surface in the first {110}crystallographic plane. In another embodiment, the depth is associatedwith a second {110} crystallographic plane in parallel to the first{110} crystallographic plane. In yet another embodiment, the secondpatterned ion-implantation is substantially similar to the firstpatterned ion-implantation. In one example, the process 820 can beperformed following the step described in FIG. 3E.

Finally, a second cleaving process (Process 822) can be performed toinitiate a film cleavage from the second cleave region through thesecond {110} plane. In one embodiment, the second cleaving process issubstantially similar to the first cleaving process. The result of thesecond cleaving process is a removal of a single crystal silicon sheet,which has a thickness determined by the depth of the second cleaveregion and a shape that is substantially the same as the cross-sectionof the silicon ingot. In a specific embodiment, the thickness of thesingle crystal silicon sheet can be controlled to be in a range of 20microns to 180 microns depending on the applications. For example, thesingle crystal silicon sheet can be applied to make one or morephotovoltaic regions directly on its surface in an {110}crystallographic plane. According to embodiments of the presentinvention, certain above processes, particularly the processes 816through 822, can be repeated in a successive manner to produce aplurality of single crystal silicon sheets, each with a desiredthickness and surfaces in an {110} plane.

FIG. 9 is a simplified flowchart showing a method of slicing a shapedcrystal ingot according to an alternative embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize many variations, alternatives, and modifications. Asshown, the method 900 includes a process (910) of providing a singlecrystal silicon boule with an axis in <110> direction and chopped at afirst end-face and a second end-face that is a length away from thefirst end-face. Both the first end-face and second end-face can besubstantially in an {110} crystallographic plane if the chopping is doneperpendicularly to the <110> axis. In addition, the silicon boule withthe length can be further cropped on its side faces. In particular, atleast one side face can be selected to be in an {111} plane. Forexample, for a silicon boule with long axis in [110] direction, one sideface can be in (−11−1) plane. Furthermore, other side faces can beselected to be either in parallel or perpendicular to the (−11−1) planeso that the cross section shape is a substantially squared shape(excepting chopped corners due to further cutting to form several minorside faces). In one example, the obtained single crystal silicon bouleis the silicon boule 400 shown in FIG. 4. Of course, there can be manyvariations, alternatives, and modifications.

Additionally, the single crystal silicon boule includes a middle crosssection plane that includes the <110> axis and is in parallel to atleast the side face in an {111} plane. In other words, the cross sectionplane itself belongs to {111} plane family. The method 900 includescutting the silicon boule along the middle cross section plane (Process912) to separate the silicon boule into a first portion and a secondportion each with a newly created surface that is substantially in an{111} plane. In a specific embodiment, the present invention provides an{111} plane based surface for layer transfer process in addition to the{110} plane based surface. For single crystal silicon, {111} plane isthe best cleave plane followed by the {110} plane. Therefore, thebenefits of the present invention, particularly the process 912,includes high productivity using low dose controlled cleave process withhigher yield and formation of the cleave plane that has lower surfaceroughness. The cleaving process detail can be further described below.In one example, the cutting process 912 can be done using a wire sawingtechnique.

In one case, the first portion cut from the single crystal silicon boule(in Process 912) is used to continue subsequent processes particularlyon the newly created surface in {111} plane. However, the cuttingusually is not perfect so that the created surface can be off a miscutangle from the true {111} plane. For example, the surface of the firstportion is miscut with an angle of 1 degree or 2 degrees off a (−11−1)plane. The method 900 then includes a process (914) of determining afirst side associated with a first edge thickness and a second sideassociated with a second edge thickness near the surface of the firstportion. In one embodiment, the first side is associated with a thinneredge thickness between the surface and a first {111} plane below thesurface with the miscut angle. Thus, the second side is associated witha thicker edge thickness between the surface and the same {111} plane.In one example, the process 914 is to use an XRD technique foridentifying the first edge thickness.

The next process is to apply a first patterned implanting process at thevicinity of the first side to form a first cleave region at the first{111} plane (Process 916). The patterned implanting process includesusing ion beam generated from a linear accelerator system to irradiatethe vicinity of the first side from the surface. The ion beam can becontrolled in terms of its energy level, beam diameter, beam current,and pulse rate etc. so that a first cleave region can be created down toa certain depth below the surface. In one embodiment, the depth can becontrolled to be substantially the same as the first edge thicknessidentified in Process 914. In another embodiment, the first cleaveregion is associated with a first {111} crystallographic plane. Forexample, the process 916 can be performed using step illustrated in FIG.3B. In another example, the process 916 is similar to the process 816.

The method 900 further includes a process (918) of performing a firstcleaving process to remove a layer of single crystal silicon materialinitiated at the first cleave region. In one embodiment, the firstcleaving process is carried out through the first {111} crystallographicplane which is a best cleave plane for single crystal silicon, which issubstantially similar to the cleaving process 818 performed on the {110}plane. In another embodiment, the Process 918 starts at the first sideand finishes at the second side of the first portion, during which ablade with sharp edge is pushed in the first cleave region while theportion of the layer of the single crystal silicon material above thefirst cleave region is pulled up at the same time. In a specificembodiment, the first cleaving process is a controlled cleave process(CCP) developed by a co-inventor.

In certain embodiments, the first cleaving process is to reveal a newsurface that is in true {111} crystallographic plane. When such asurface is exposed, a second patterned implanting process (Process 920)can be applied at the vicinity of the second side to form a secondcleave region at a second {111} plane that is in parallel to the exposedsurface. In one embodiment, the second patterned implanting process issubstantially the same as the first patterned implanting process (916)with a controlled ion beam parameters to form the second cleave regionin a desired depth. In another embodiment, the desired depth isassociated with the second {111} plane. In one example, the secondpatterned implanting process is carried out at the second sideidentified in Process 914.

Subsequently, the method 900 includes a second cleaving process (Process922) being performed to remove a single crystal silicon sheet initiatedat the second cleave region. In one embodiment, the second cleavingprocess includes performing a CCP process through the second {111}crystallographic plane using a blade with sharp edge assisted withultrasonic mechanical energy from top. In another embodiment, theProcess 922 causes the formation of the single crystal silicon sheethaving an {111} crystallographic plane, which is an alternative type ofthe single crystal silicon sheet that can be produced from a siliconboule with an <110> axis. The single crystal silicon sheet formedincludes a thickness ranging from 20 microns to 180 microns which can beused for various semiconductor applications including photovoltaiccells. In yet another embodiment, the Process 922 is substantiallysimilar to the process 822 performed on the {110} plane. According toembodiments of the present invention, certain above processes,particularly the processes 916 through 922, can be repeated in asuccessive manner to produce a plurality of single crystal siliconsheets, each with a desired thickness and surfaces in {111} plane. Oneach of the {111} type surfaces one or more photovoltaic regions can beformed in one or more subsequent processes.

Referring to FIG. 8 and FIG. 9, the Process 816 or 916 is implemented asa preferred step in the whole cleave process sequence aiming to reducedcost and achieve desired productivity, yield, and quality goals. Insteadof performing implantation on the whole sample area, embodiments ofcurrent invention based on patterned implantation allow a smallerlocalized initiation dose to be placed at an edge or corner of the bouleor tile of silicon. For example, as shown in FIG. 3B and FIG. 3E, iondose is applied to a limited area for each silicon boule or tile forforming a cleave region from which the cleaving action can be started.Additionally, embodiments of present invention provides a method forperforming patterned ion implantation for multiple samples atsubstantially same time, aiming for further process optimization in highvolume manufacture production. FIG. 10 is a simplified diagram showing a4×4 tray arrangement of silicon ingots for forming spot initiation ofcleave regions using patterned ion implantation according to analternative embodiment of the present invention. This diagram is merelyan example, which should not unduly limit the scope of the claimsherein. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications. As shown, each siliconboule or tile is in a square shape with truncated or rounded corners andfour such boules or tiles 1001, 1002, 1003, and 1004 are disposed in a4×4 tray arrangement in this top view so that four corner regions arenearby with close proximity. In one embodiment, an initiation ion doseis placed at either an edge or a corner of the tile, because it isadvantageous for naturally providing side access for propagation and thefracture mechanics also favors edge initiation and propagation from anedge. In this case, corner region is selected to be the initiationcleave region. Thus, an ion beam (not directly shown) with predetermineddose and energy level is applied over the four corner regions that areclosely arranged, forming four cleave regions 1051, 1052, 1053, 1054corresponding to the four silicon boules 1001, 1002, 1003, and 1004respectively. The formation of the initiation cleave region can becarried out, for example, by executing the Process 816 of the method 800or the Process 916 of the method 900. Of course, there are manyvariations, alternatives, and modifications. For example, the ion beamspot size may vary, the beam may need to scan around the four cornerarea if necessary depending on specific mechanical shape or desired sizeof cleave regions.

FIG. 11 is a simplified diagram showing a 4×4 tray arrangement ofsilicon ingots for forming line initiation of cleave regions usingpatterned ion implantation according to an alternative embodiment of thepresent invention. This diagram is merely an example, which should notunduly limit the scope of the claims herein. One of ordinary skill inthe art would recognize many variations, alternatives, andmodifications. As shown, the silicon boules or tiles 1101, 1102, 1103,1104 are arranged in the same manner of a 4×4 arrangement as in FIG. 10,however, the edge region instead of corner region is selected to formthe initiation cleave region. Thus the ion beam is applied over regionswhere two edge regions 1151 and 1152 of two neighboring boules 1101 and1102 are close by a proximity distance. Then, the beam can be scanneddown the line to cover additional edge regions 1153 and 1154 for asecond pair of silicon boules 1103 and 1104, and further to a thirdpair, and so on.

In one embodiment of current invention, high energy H ions generatedfrom a linear accelerator system are used forming the initiation cleaveregion. The beam current can be about 2 mA and particle energy isaccelerated to 4 MeV range. The H-dose is large enough that once theinitiation cleave region is formed a thermal process allows cleavingaction to start from the cleave region without much additional energyapplication. In an specific embodiment, it is found that the initiationaction fails to function if the H-dose is below about a 4.5×10¹⁶ cm⁻² to5×10¹⁶ cm⁻² range.

In another embodiment, as a 5×10¹⁶ cm⁻² dose is applied over 1.5 cm×1.5cm edge or corner area, the implant current needed is about 1-2 mA.Compared to a 15 cm squared tile, the patterned implantation takes just1% of total area of the tile. For average dose of 1×10¹⁶ cm⁻², in orderto cover the whole area of tile, a 20 mA beam current is required.Therefore, there is a large advantage to be gained by reducing the dosefor rest area excepting the initiation cleave region or even completelycutting off the beam. Purposely selecting {111} or {110} planes forpropagation of the thick film according to certain embodiments make itpossible. In one embodiment, the H-dose for thermal propagating can bereduced down to about 2-3×10¹⁶ cm⁻², even the cleave plane is off fromthe most desired crystallographic planes. For certain cleave plane witha slightly miscut angle from true (111) planes, the minimum ion dose canbe further reduced to slightly above 1×10¹⁶ cm² range. Furthermore, fora cleave plane along true (111) crystallographic plane, in principle,the ion dose can be reduced substantially low of zero dose. Effectively,this enhances the productivity for high volume manufacturing.

In a specific embodiment, the present method can perform otherprocesses. For example, the method can place the removed single crystalsilicon sheet on a support member, which is later processed.Additionally or optionally, the method performs one or more processes onthe semiconductor substrate before subjecting the surface region withthe first plurality of high energy particles. Depending upon theembodiment, the processes can be for the formation of photovoltaiccells, integrated circuits, optical devices, any combination of these,and the like. Of course, there can be other variations, modifications,and alternatives.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Although the above has been described using a selected sequence ofsteps, any combination of any elements of steps described as well asothers may be used. Additionally, certain steps may be combined and/oreliminated depending upon the embodiment. Furthermore, the type of ions,which are typically hydrogen ions, can be replaced using co-implantationof helium and hydrogen ions or deuterium and hydrogen ions to allow forformation of the cleave region with a modified dose and/or cleavingproperties according to alternative embodiments. Still further, thecleaving process may include temperature controlled/assisted cleavingutilizing vacuum chucking or electrostatic chucking process. Of coursethere can be other variations, modifications, and alternatives.Therefore, the above description and illustrations should not be takenas limiting the scope of the present invention which is defined by theappended claims.

What is claimed is:
 1. A shaped crystalline ingot for an ion cleavingprocess, the shaped crystalline ingot comprising: a major surface thatis substantially planar; a first side face that is substantially planaralong a first direction orthogonal to the major surface; and a secondside face that is substantially planar along a second directionorthogonal to the major surface, wherein the ion cleaving process is aprocess in which ions are implanted into the shaped crystalline ingot toform a cleave plane that separates a substrate comprising the majorsurface from the shaped crystalline ingot.
 2. The shaped crystallineingot of claim 1, wherein the shaped crystalline ingot is cut from acrystalline material boule that has a cropped structure including afirst end-face, a second end-face, and a length along an axis in acrystallographic direction substantially extending from the firstend-face to the second end-face, wherein the first and the second sidefaces correspond to the first end-face and the second end-face of thecrystalline material boule, respectively, and wherein the major surfaceis parallel to the axis.
 3. The shaped crystalline ingot of claim 1,further comprising: a first corner face extending from the first sideface to the second side face; and a second corner face extending fromthe first side face to the second side face, the second corner facebeing separate from the first corner face, wherein the first corner facedefines a first obtuse angle with a back surface that is parallel to andseparate from the major surface, and the second corner face defines asecond obtuse angle with the back surface.
 4. The shaped crystallineingot of claim 2, wherein the crystallographic direction is selectedfrom the group consisting of <100>, <110>, and <111>.
 5. The shapedcrystalline ingot of claim 1, wherein the crystalline material comprisesa semiconductor.
 6. The shaped crystalline ingot of claim 1, wherein thecrystalline material comprises silicon.
 7. The shaped crystalline ingotof claim 2, wherein the first end-face corresponds to a first cuttingplane of a crystalline material ingot along a first cross sectionperpendicular to the crystallographic direction, and the second end-facecorresponds to a second cutting plane of the crystalline ingot along asecond cross section perpendicular to the crystallographic direction,wherein the shaped crystalline ingot has a substantially squared crosssection shape with at least one side face in one crystallographic plane,which is obtained by cropping partially side-sections of the crystallineingot, and wherein the crystalline ingot is grown in thecrystallographic direction.
 8. The shaped crystalline ingot of claim 7wherein the squared cross section shape comprises a dimensionsubstantially equal to the length along the axis in the crystallographicdirection.
 9. The shaped crystalline ingot of claim 2, wherein theshaped crystalline ingot is obtained by cutting a crystalline materialboule using a wire saw.
 10. The shaped crystalline ingot of claim 1,wherein the major surface comprises a miscut angle off from onecrystallographic plane, the miscut angle being 0 to 2 degrees.
 11. Theshaped crystalline ingot of claim 1, wherein the major surface of theshaped crystalline ingot is exposed by a first side associated with afirst edge thickness from the major surface to a crystallographic planewithin the shaped crystalline ingot and a second side associated with asecond edge thickness from the major surface to said crystallographicplane, the first edge thickness being smaller than the second edgethickness.
 12. The shaped crystalline ingot of claim 11, wherein the ioncleaving process comprises a first implanting process to perform apatterned ion-implantation at a vicinity of the first side to form afirst cleave region at the first edge thickness below the major surface.13. The shaped crystalline ingot of claim 12, wherein the ion cleavingprocess further comprises a first cleaving process initiated at thefirst cleave region to remove a layer of crystalline material from thefirst side to the second side in one first crystallographic directionwithin the crystallographic plane.
 14. The shaped crystalline ingot ofclaim 13, wherein the first cleaving process comprises using a movableblade with sharp edge and assisting ultrasonic energy with the movableblade.
 15. The shaped crystalline ingot of claim 12, wherein the ioncleaving process further comprises a second implanting process toperform a patterned ion-implantation at a vicinity of the second sideafter the first cleaving process to form a second cleave region at apredetermined thickness below the first cleave region.
 16. The shapedcrystalline ingot of claim 15, wherein the ion cleaving process furthercomprises a second cleaving process initiated at the second cleaveregion, the second cleaving process being substantially similar to thefirst cleaving process, to remove a crystalline material sheet.
 17. Theshaped crystalline ingot of claim 16, wherein a thickness of thecrystalline material sheet is from 20 microns to 180 microns.
 18. Theshaped crystalline ingot of claim 16, wherein the ion cleaving processis further carried out in a successive manner by repeating the secondimplanting process and the second cleaving process to remove theplurality of crystalline material sheets one after another.
 19. Theshaped crystalline ingot of claim 18, wherein each of the plurality ofthe crystalline material sheets includes one or more photovoltaicregions formed thereon.